Current machines for fixing components are of the conveyor belt and oven type. In a machine of this type, the substrates on which only those components that do not pass therethrough have been positioned for soldering are themselves placed on the conveyor belt which is in the form of a metal mesh or net. These substrates are then taken into the oven and pass therethrough on the belt which is continuously driven. The substrates thus pass a short distance above the heat sources in the oven which apply increasing temperatures thereto following a working cycle defined by preheating, heating and soldering operations with the temperature generally rising in stages. The substrates are then conveyed by the same belt to a cooling station, eg. an air blower, to ensure rapid solidification of the solder joints and to cool the substrates to ambient temperature.
Such machines can only be used to fix components which do not pass through the substrate, and they therefore suffer from a first drawback of requiring components that pass through the substrate to be fixed manually afterwards.
Further, since heat is transmitted from each of the sources to the substrates through the belt, the oven also includes additional heat sources disposed above the belt in order to compensate heat dissipation and to improve the rise in temperature according to the defined cycle. Unfortunately, these additional heat sources have the drawback of also raising the temperature of the bodies, ie. the sensitive portions of the components, substantially up to the temperature of the solder joints. Such a rise in temperature of the sensitive portions of the components is excessive, and may degrade the components or may be the cause of premature ageing, at least for some components.
In such a machine the conveyor belt which is driven continuously is also the source of vibration which is transmitted directly to the substrates. Such vibration, even if only of small amplitude, is particularly damaging at the instant of solder solidification, and therefore has an effect on the quality of the solder joints made.
Also, in such a machine the rise in temperature by stages may also constitute a drawback in particular in some applications in which for reasons of reliability the components must not be subjected to heat shock.
Preferred embodiments of the present invention enable all components, including components that pass through the substrate, to be fixed in a single operation. Such embodiments of the invention also avoid the other drawbacks mentioned, and thereby enable reliable hybrid circuits.